P1655

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION
The EGR flow is controlled by the vacuum actuated EGR valve. The EGR pulse width modulated solenoid meters the vacuum level at the EGR valve actuator as commanded by the Powertrain Control Module (PCM). When the PCM is commanding the EGR solenoid ON, the voltage potential of the circuit will be low (near 0 volts). When the PCM is commanding the EGR solenoid OFF, the voltage potential of the circuit will be high (near battery volts). The primary function of the PCM in this circuit is to supply the ground for the EGR solenoid. This is a type B code.

CONDITIONS FOR SETTING THE DTC
- PCM requested EGR solenoid ON.
- Voltage on EGR solenoid control circuit high (near battery volts).
- 2 consecutive faults detected.
- Conditions met for 2 seconds.
or
- PCM requested EGR solenoid OFF.
- Voltage on EGR solenoid control circuit low (near 0 volts).
- 2 consecutive faults detected. Conditions met for 2 seconds.

ACTION TAKEN WHEN THE DTC SETS

- No EGR.
- Possible black smoke on acceleration.

CONDITIONS FOR CLEARING THE MIL/DTC
- The PCM will turn the MIL off after three consecutive trips without a fault condition.
- A History DTC will clear when forty consecutive warm-up cycles that the diagnostic does not fail (coolant temperature has risen 5°C (40°F) from start up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle.

DIAGNOSTIC AIDS
The scan tool has a 5 second ON time abort. The EGR solenoid can be commanded ON for as many times as needed, in 5 second intervals. Its possible other EGR DTCs may set along with DTC P1655. This diagnostic can be checked at key up. A quick operational check can be made by commanding the EGR solenoid ON and OFF with the scan tool while monitoring Actual EGR. Actual EGR will display Barometric Absolute Pressure (BARO) (approximately) when EGR solenoid is OFF. Full EGR will be achieved when EGR solenoid is commanded ON with the scan tool.

TEST DESCRIPTION
Number(s) below refer to the Step number(s) on the Diagnostic Table.

2. Be sure that both the ON and OFF states are commanded. Repeat the commands as many times as necessary. This Step will determine if this DTC is a current or intermittent.
3. This check can detect a partially shorted coil which would cause excessive current flow. Leaving the circuit energized for 2 minutes allows the coil to warm up. When warm, the coil may open (Amps drop to zero, or short (Amp draw greater than 0.75A).
7. Listen for an audible click when the solenoid operates. This Step checks the ignition feed circuit for an open.